This invention relates to improvements in winches and relates particularly to an improved winch construction adaptable for use on marine vessels, particularly sailing craft.
Winches are currently used on sailing craft of all types to facilitate the hauling of sheets, halyards and other tackle for the control of sail settings and the like. Hand operated winches generally have a ratchet mechanism operated by a handle which may be either fixed to the winch or removable therefrom. The handles on fixed lever winches often cause obstruction to crew movement and can also cause tangling of deck sheets. The fixed lever winches generally have a relatively short arc handle which either requires a relatively high gearing ratio to allow the necessary forces to be applied to the sheets or a relatively large turning force is required to operate the winch.
Winches having a removable handle generally have a handle of greater length than the short arc fixed lever handles to enable a larger turning force to be applied to the winch. However, the removable handles need to be able to be stored remotely from the winch which can result in handles being lost. Further, valuable time is sometimes lost in fitting the handles to the winch in the correct manner.
It is well known to provide winches with internal gearing, and clutch or ratchet mechanisms, to provide a mechanical advantage between movement of the operating lever or handle and rotation of the winch drum. Australian patent specification No. 429,190 discloses a three-speed deck winch wherein rotation of an input shaft by means of a handle in one direction results in selective engagement of internal gearing to drive the winch drum in a given direction at a first speed which is different to that when the input shaft is rotated in an opposite direction to cause operative engagement of second gearing, and a further engagement means enables the driving means for the input shaft to be directly coupled to the winch drum to drive the drum at a third speed. The direct coupling mode of this winch is manually selected so that pawls, pins, lugs or the like are moved to a position such that the handle or other driving means directly engages with the drum.
Australian patent specification No. 454,362 discloses a similar form of two-speed winch in which an operating handle on the top of the winch drives the winch drum, through gearing and clutch means located in the base of the winch to rotate the winch drum in a given direction at a first speed on rotation of the handle in a first direction and to rotate the winch drum at a second speed on rotation of the handle in the opposite direction. Specification No. 456,935, which is additional to No. 454,362, discloses a modified arrangement in which the input shaft may be directly coupled to the winch drum to provide an additional 1:1 gear ratio.
Australian patent specification No. 487,866 discloses a further arrangement of multi-speed winch in which a pawl is carried by the winch handle to directly couple the winch handle to the drum in an operative position and whereby, in an inoperative position, the winch handle drives the drum in a given direction at one of two speeds dependent on the direction of movement of the winch handle.
Australian patent specification No. 496,573 also discloses a multi-speed winch in which an idler gear, movable on a pivoted carrier, is able to be moved manually into engagement with a main shaft gear and a drum driving gear to drive the drum at a first speed on rotation of the winch handle. Reverse rotation of the handle automatically releases the idler gear from its engaged position and the winch drum is then driven at a second speed, or a third speed on further reverse of the handle rotation direction, by means of the gearing and associated clutches, etc., located in the base of the winch. The idler gear is moved by means of a lever mounted on the base of the winch.
The winches described in the prior art referred to above are all driven either by a handle mounted on the top of the winch and driving through an input shaft extending through the winch drum or, as shown in the Specification No. 429,190, through a pedestal arrangement which drives the input shaft by means of a chain and sprocket. The prior art winches are all, therefore, relatively expensive to manufacture due to the need to provide a multiplicity of internal seals and bearings which necessitate relatively expensive machining of the drum, shafts and other components.
Further, notwithstanding the use of seals, the prior art winches are susceptible to moisture entering the internal cavities of the winch resulting in corrosion and lack of durability of the winch. Further, the winches are operated by top-mounted handles which must be rotated in a particular direction for a desired gear ratio thus causing difficulty for the operator in providing the necessary circular motion to the handle.
It is desirable to provide an improved construction of winch which avoids some or all of the difficulties associated with the known handle operated winches.
It is also desirable to provide an improved construction of winch which has a sealed top to prevent the egress of moisture into the winching mechanism and which also obviates the need for a multiplicity of internal seals.
It is also desirable to provide an improved construction of winch which is relatively simple to operate and is economical and relatively cheap to manufacture.